The present invention concerns specific composite, roof-ceiling constructions whereby no simillar solution is know. All the adventages given by the present innovation are enabled owing to the solution of the prestressing method that makes them applicable to large spans suitable for constructing of industrial buildings.
All custom concrete-prestressing methods are adapted to concrete specificities with adapted cross-section shapes whereby indroducing of the prestressing force in a lower zone of the beams, trusses or plates, due to compressive force acting on eccentricity below the gravity center of the cross section, problem of deflections and cracks is solved simultaneously. Several ways of prestressing are customizable in constructing steel buildings whereby some elements of trusses are forced mechanicaly or thermally to introduce prestressing effects.
The above mentioned prestressing methods are well known and are applied to one-material constructions, adapted thereby to its specific characteristics. These constructions, because of their specificities that they have as a composite, made of concrete and steel parts, can not be compared, under the criterion of prestressing effects, to usual ones whereby several technical solutions are applied in the same sense, to introduce the prestressing force below the gravity center of the cross-section.